Gadgetbridge/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/supercars/JoystickView.java

/*  Original code taken from https://github.com/efficientisoceles/JoystickView
    Licenced under the terms of the GNU General Public License version 3
    Copyright (C) Daniel Su <goldenember@gmail.com>
 */
package nodomain.freeyourgadget.gadgetbridge.devices.supercars;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;

import nodomain.freeyourgadget.gadgetbridge.GBApplication;
import nodomain.freeyourgadget.gadgetbridge.R;

public class JoystickView extends SurfaceView implements SurfaceHolder.Callback, View.OnTouchListener {
    private float centerX;
    private float centerY;
    private float baseRadius;
    private float hatRadius;
    private JoystickListener joystickCallback;
    private final int ratio = 5;

    private void setupDimensions() {
        centerX = getWidth() / 2;
        centerY = getHeight() / 2;
        baseRadius = Math.min(getWidth(), getHeight()) / 3;
        hatRadius = Math.min(getWidth(), getHeight()) / 5;
    }

    public JoystickView(Context context) {
        super(context);
        getHolder().addCallback(this);
        setOnTouchListener(this);
        if (context instanceof JoystickListener)
            joystickCallback = (JoystickListener) context;
    }

    public JoystickView(Context context, AttributeSet attributes, int style) {
        super(context, attributes, style);
        getHolder().addCallback(this);
        setOnTouchListener(this);
        if (context instanceof JoystickListener)
            joystickCallback = (JoystickListener) context;
    }

    public JoystickView(Context context, AttributeSet attributes) {
        super(context, attributes);
        getHolder().addCallback(this);
        setOnTouchListener(this);
        if (context instanceof JoystickListener)
            joystickCallback = (JoystickListener) context;
    }

    private void drawJoystick(float newX, float newY) {
        if (getHolder().getSurface().isValid()) {
            Canvas myCanvas = this.getHolder().lockCanvas();
            Paint colors = new Paint();
            myCanvas.drawColor(GBApplication.getWindowBackgroundColor(getContext()));

            float hypotenuse = (float) Math.sqrt(Math.pow(newX - centerX, 2) + Math.pow(newY - centerY, 2));
            float sin = (newY - centerY) / hypotenuse; //sin = o/h
            float cos = (newX - centerX) / hypotenuse; //cos = a/h

            colors.setColor(this.getResources().getColor(R.color.primarydark_light));
            myCanvas.drawCircle(centerX, centerY, baseRadius, colors);

            colors.setColor(this.getResources().getColor(R.color.chart_deep_sleep_light));

            myCanvas.drawCircle(newX - cos * hypotenuse * (ratio / baseRadius) * 30,
                    newY - sin * hypotenuse * (ratio / baseRadius) * 30, 100, colors);

            colors.setColor(this.getResources().getColor(R.color.accent));
            myCanvas.drawCircle(newX, newY, hatRadius, colors);

            getHolder().unlockCanvasAndPost(myCanvas);
        }
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        setupDimensions();
        drawJoystick(centerX, centerY);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }

    public boolean onTouch(View v, MotionEvent e) {
        if (v.equals(this)) {
            if (e.getAction() != MotionEvent.ACTION_UP) {
                float displacement = (float) Math.sqrt((Math.pow(e.getX() - centerX, 2)) + Math.pow(e.getY() - centerY, 2));
                if (displacement < baseRadius) {
                    drawJoystick(e.getX(), e.getY());
                    joystickCallback.onJoystickMoved((e.getX() - centerX) / baseRadius, (e.getY() - centerY) / baseRadius, getId());
                } else {
                    float ratio = baseRadius / displacement;
                    float constrainedX = centerX + (e.getX() - centerX) * ratio;
                    float constrainedY = centerY + (e.getY() - centerY) * ratio;
                    drawJoystick(constrainedX, constrainedY);
                    joystickCallback.onJoystickMoved((constrainedX - centerX) / baseRadius, (constrainedY - centerY) / baseRadius, getId());
                }
            } else if (e.getAction() == MotionEvent.ACTION_UP) {
                drawJoystick(centerX, centerY);
                joystickCallback.onJoystickMoved(0, 0, getId());
            } else
                drawJoystick(centerX, centerY);
            //joystickCallback.onJoystickMoved(0, 0, getId());
        }
        return true;
    }

    public interface JoystickListener {
        void onJoystickMoved(float xPercent, float yPercent, int id);
    }
}